Co-immobilization of two-component hydroxylase monooxygenase by functionalized magnetic nanoparticles for preserving high catalytic activity and enhancing enzyme stabilty.

Cascade reactions catalyzed by two or more enzymes have been widely used in industrial production and exhibited many advantages over the single-enzyme catalytic system. In this study, two components of hydroxylase monooxygenase (HpaBC) were first co-immobilized by Ni-nitrilotriacetic acid (Ni-NTA) functionalized magnetic silica nanoparticles (Ni-NTA/HN-SiO@FeO) for enhancing the stability and activity of biocatalysts with multi-components. These two components, HpaB and HpaC, were modified with histidine-tag and employed to construct a bi-enzyme catalytic system. After co-immobilization, the activity of the bi-enzyme system was 2.6 times of free enzymes. Meanwhile, the co-immobilized system was more stable against high temperature and alkaline condition, and maintained 76.6% of the initial activity for storage 12 days. Moreover, the co-immobilized HpaBC remained more than 60% catalytic activity after 7 cycles. These results showed that co-immobilized multi-component enzymes based on functionalized magnetic nanoparticles without purification would play a great potential role in the field of industrial biocatalysis.